Enhanced mechanical properties and corrosion behavior of polypropylene/multi-walled carbon nanotubes/carbon nanofibers nanocomposites for application in bipolar plates of proton exchange membrane fuel cells

Polypropylene (PP) nanocomposites with multi-walled carbon nanotubes (MWCNT) alone or combined with carbon nanofibers (CNF) at different loadings have been fabricated by melt mixing with a focus on their mechanical properties and corrosion resistance for bipolar plates applications in proton exchange membrane fuel cells (PEMFCs). The incorporation of up to 20 wt% MWCNT in the PP matrix produces enhancements of 71, 47, 56, and 30% in microhardness, elastic modulus, and tensile and flexural strength, respectively. Combined additions of MWCNT and CNF allow producing hybrid nanocomposites with increased strength than when neat MWCNT as reinforcement, preserving their processability even at a total filler content of up to 30 wt%. The measured values of i_corr in both PP/MWCNT and PP/MWCNT/CNF suggest a slow degradation rate in the PEMFC environment. Based on the US Department of Energy (DOE) targets, PP/20MWCNT, PP/21.5MWCNT, and PP/15MWCNT/15CNF nanocomposites are good candidates to produce bipolar plates for PEMFCs.